Manganese alloy



Patented Oct. 21, 1941 MANGANESE ALLOY Reginald s. Dean, Washington, D. 0., assignor to Chicago Development Company, Chicago, 111.,

a corporation of Illinois No Drawing. Application October 22, 1939,

Serial No. 300,799

Claims.

My invention relates to alloys of manganese with improved mechanical properties and is particularly concerned with the production of alloys having high yield point, high vibration damping capacity and correspondingly large elastic hysteresis. It further relates to methods of improving the yield point and damping capacity of alloys.

In my copending application, Serial No. 267,708,

filed April 13,1939, of which the present application is a con'tinuation-in-part, I have disclosed alloys, containing large proportions of manganese, which have exceptionally high vibration damping capacity. In said copending application, I have disclosed alloys having high strength and high vibration damping capacity, having particularly utility, among other things, for structural elements such as gears and springs for use in the automotive, railroad and other industries, and other machine elements, as' well as for sheet and foil for use as acoustic insulators and the like. Said alloys contained more than 10% and up to 98'% manganese, balance substantially entirely copper, said alloys preferably containing not substantially less than 80% manganese, said alloys being preferably heat treated and having a vibration damping capacity of not substantially less than 3% of the maximum applied energy per cycle. Furthermore, as disclosed in said copending application. for best results said alloys are prepared from electrolytic manganese and the preferred embodiments have a Rockwell C hardness of at least 25. I have found also that by suitable mechanical and heat treatment the damping capacity of these alloys can be increased and that other alloys having relatively low damping capacity can be greately improved in this respect by mechanical or heat treatment. I have found that these treatments also improve other mechanical properties, particularly yield point.

, I have found that my treatment for improving the damping capacity and yield point of alloys may be applied with especially valuable results to the following composition ranges of alloys:

Other alloys with more than 35% manganese "such as those containing copper and aluminum,

copper and nitrogen, and copper and chromium, as well as quaternary and higher alloys having a considerable proportion of manganese. It will be understood that, in the numerical values given above, the total of the alloying constituents in each case equals approximately 100.

I have found that all of these alloys, when quenched from a high temperature but below the melting point, are in a state of inchoate high damping capacity.

In some'of the alloys, this capacity may be evident in the quenched alloy, particularly if the alloy is oil quenched. I have found, however, that in all cases the damping capacity is enhanced by subjecting the alloys to stress sufficient to produce a length change of a few thousandths of an inch per inch when the stress is removed. I have found that this set disappears with time, it. being apparently not an inelastic deformation but an elastic one which remains after the stress is removed because of the very high internal friction of the alloys. If the stress is increased so as to cause true inelastic deformation, the increased damping capacity is again lowered. Increased damping capacity produced in this way gradually decreases with time so that to make the maximum effective use of my invention the machine element or the like made from these alloys must be subjected in the course of its use to suitable stresses repeated at frequent intervals.

I have found that the quenched alloys may be given a damping capacity that will not fall ofi noticeably with time by heating to a temperature between about 300 degrees C. and 600 degrees C. In many instances, this stabilizing treatment also increases damping capacity and limit of usable stress.

The following table gives a number of illustrations of my invention as it relates to composition-heat treatment of alloys.

On standing after applying 50,000 lbs/sq. in.,

the damping returned to 1.75 in eighteen hours.

with regard to the eifect on stability of quenching in various media and of reheating, I have found that oil is most effective inproducing high damping capacity immediately after quenching but that the highest stable values are obtained by reheating after quenching. The following examples will illustrate my invention in this regard (the alloy composition was 90 Mn 10 Cu):

Composition 1d 0 o o o quenched worked 450 C. 600 C. 700 0. Mn Cu Ni Zn Sn Dumpling Damping Damping Cooling method immed tely 48 hours. 96 hours after cooling later later 40 Per cent Per cent Per cent Blow cool 1. 33 3 1. 3 Czuench in oil ll. 1 5. 1 3. 2 C uench in ice brine 3. 2 2. 72 2. 70 Quench in water 4. 1 2. 96 2. 90 Quench in water heated 2 hrs. 5 3. 7 3. 7 3. 7

tained 65% manganese, 30% copper and 5% After applying 80,000 lbs/sq. in., the damping dropped to 1.30% in eighteen hours.

The maximum stress which may be applied without loss of damping capacity varies with the alloy and the treatment. In general, it is approximately 50% of the ultimate tensile strength.

All of the alloys of my invention may be improved in tensile strength and yield point by suitable heat treatment. Forthe alloys of my invention containing less than 75% manganese, I have found that a suitable heat treatment comprises quenching from above 800 degrees C. and reheating from about 400 degrees C. to about 500 degrees C. For alloys of my invention which contain more than 75% manganese, I have found that somewhat greater yield point and hardness may be obtained by using aging temperatures from 600 degrees C. to 800 degrees C. This improvement in hardness and yield point does not appear to be accompanied by a corresponding increase in ultimate strength. The following example will illustrate the application of my invention.

Composition ig iii g fi Hardening hardened, lbs. per d 0 Mn Ni Cu Zn Sn sq. in. Quenched Hardened eg'ees nickel. Damping capacity after heating to 450 degrees C., 1.75%. After applying Percent 10,000 lbs./sq. in. tension 1.89

20,000 1bs./sq. in. tension 1.95 70 30,000 lbs./sq. in. tension 1.92

50,000 lbs/sq. in. tension 2.09

60,000 lbs/sq. in. tension 1.95

70,000 lbs/sq. in. tension 1.73 80,000 lbs/sq. in. tension 1.30

I have found it especially desirable to utilize a highly pure manganese, namely, one containing at least about 99.5% manganese. Electrolytic manganese has been found to be unusually satisfactory for use in all of the alloys'of my invention, particularly with regard to the alloys having a content of at least 70% manganese.

The alloys of my present invention may be employed for various purposes which will be clear to those in the art in the light of my description of their properties. As illustrative of uses thereof may be mentioned water-pipe and other pipe sections to decrease transmission of noises. along the same, railroad track sections to prevent ripple formations, ship and submarine armor, and the like.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. A quenched and aged'alloy, having a vibration damping capacity of more than 0.1%, said alloy containing at least 90% electrolytic manganese having a purity of at least 99.5%, and the balance copper.

2. A manganese copper alloy, having a vibration damping capacity of more than 0.1%, said alloy containing at least 60% electrolytic manganese having a purity of at least 99.5%, and the 3. A structural element for use in an environment requiring a high vibration damping capacity, said structural element being made from an alloy containing from 35% to 97% manganese, and the balance being substantially entirely copper, said alloy having a vibration damping capacity of more than 0.1%.

4. A structural element for use in an environment requiring a high vibration damping capacity, said structural element being made from a quenched and aged alloy having high tensile strength, yield point and vibration damping capacity, said alloy containing from 35% to 97% manganese, and the balance being substantially entirely copper, said alloy having a vibration damping capacity of more than 0.1%.

5. A structural element for use in an environment requiring a high vibration damping capacity, said structural element being made from an alloy containing more than 70% and up to 98% manganese, and the balance being substantially entirely copper, said alloy having a vibration damping capacity of not substantially less than 3% of the maximum applied energy per cycle.

6. A structural element for use in an environment requiring a high vibration damping capacity, said structural element being made from a 'heat treated alloy containing more than 70% and up to 98% manganese, and the balance being substantially entirely copper, said alloy having a vibration damping capacity of not substantially less than 3% of the maximum applied energy per cycle and a Rockwell-C hardness of at least 25.

7. A structural elementior use in an environment requiring a high vibration damping capacity, said structural element being made from an alloy consisting of approximately 80% manganese and the balance copper, said alloy having a vibration damping capacity of not substantially less than 3% 01 the maximum applied energy per cycle. i

8. A structural element for use in an environment requiring a'lhigh vibration damping capacity, said structural element being made from a heat treated, hardened alloy consisting of approximately 80% manganese and the balance copper, said alloy having a vibration damping capacity of not substantially less than 3% of the maximum applied energy per cycle.

9. A structural element in the form of a spring, said spring being made of an alloy consisting of not substantially less than 80% manganese, balance copper, the copper constituting at least 2% of the alloy, said alloy having a vibration damp- 1 ing capacity of at least about 3% of the maximum 

